1. Field of the Invention
This invention relates to laundry machines, and more particularly to such machines that are combination washer-dryers.
2. Description of the Prior Art
Combination washer-dryers are machines which provide for complete laundering of clothes, that is, they provide a washing operation which includes washing and rinsing, a centrifugal extraction or spin operation for removing a substantial part of the water from the clothes, after the wash operation, and a complete drying of the clothes, generally effected by tumbling the clothes in the presence of warm air. One of the difficulties with these combination washer-dryers is the method and apparatus necessary to extract the water after the washing operation. For instance, centrifugal extraction at high speeds which is desirable for maximum liquid removal forces liquid radially outward through the materials and has the effect of the clothes adhering to the inner surface of the clothes containing drum even after the drum ceases to rotate. Inasmuch as the heat drying of the materials is dependent upon their being tumbled so as to continually present different surfaces to the circulating air, it will be readily seen that, if the materials adhere to the container after the centrifugal operation, the necessary tumbling will not occur and drying will not be effected. Moreover, the entire machine must be constructed to withstand the very substantial forces involved in high speed rotation of a substantially but not necessarily balanced mass, as well as special speed transmission means being required to provide different speeds for washing and spinning.
Some machines have avoided this problem by removing the water from the drum by means of suction. One such laundry machine is shown in U.S. Pat. No. 3,050,975, assigned to the same assignee as the present invention, wherein after the washing operation is completed then a substantial amount of suction is operative at the bottom of the drum as it is rotated and after the liquid content of the clothes has been brought down, the regular heat drying operation is begun. That is, the clothes are tumbled in the rotating drum as warmed air is circulated through the clothes.
Another combination washer-dryer is shown in U.S. Pat. No. 3,344,447 wherein after or during the clothes within the drum have been subjected to a washing operation, vacuum is drawn on the drum through a plurality of peripheral passageways that are connected to the interior of the drum and the wash water is extracted, then vacuum and/or heated air continues to dry the clothes for the remainder of the drying operation.
One of the difficulties with combination washer-dryer laundry machines is that a long period of time is required for the complete sequential washing and drying operations. For a given amount of time more loads of clothes can be dried in a separate washer and dryer than in a combination washer-dryer for the simple reason that while one load is being dried another may be washing.
It is desirable to be able to have a combination washer-dryer laundry machine that will wash clothes well yet accomplishes the washing operation with less water and less detergent than a conventional washing machine. Such a laundry machine must also be efficient in operation, low in manufacturing cost, and economical to operate in order to also make it desirable.
By our invention all of the above desirable characteristics of a laundry machine may be achieved.